Nucleic Acids Flashcards
Fred Griffith
discovered transformation
pneumococci R strain
no capsule, not pathogenic
pneumococci S strain
pathogenic, encapsulated
transformation of pneumococci
combined harmless R bacteria with heat-killed S bacteria –> R turned to S and caused pneumonia
Avery, McCarty, MacLeod
identified that DNA was the transforming principle
Hershey and Chase
used bacteriophages to determine if genetic information was DNA or protein
Hershey and Chase experiment
labeled one batch of phage with S (in protein) and one with P (in DNA) –> bacteria infected with phage –> centrifugation –> P was found in bacteria but S was found in supernatant
DNA base pairing
A with T and C with G
Watson-Crick model of DNA
bases are on inside, phosphate backbone on outside; 3.4A between bases, 10.6A per turn
Meselson-Stahl
found out that DNA was semi-conservative
Meselson-Stahl experiment
grew E. coli for several generation with N15 as only nitrogen source –> shift to N14 –> isolate DNA at various times –> weigh by centrifugation
What are genes?
a discrete region of DNA that encodes functional RNA with coding and regulatory regions
central dogma violations
RNA viruses (RNA –> RNA), retroviruses (RNA –> DNA), non-protein genes (RNA –> function), epigenetics
roles of DNA
storage of genetic information and structure
roles of RNA
storage of genetic information, structure, transfer of information, information interpretation, enzymes, gene regulation
Watson-Crick model
helical molecule will give an X-ray diffraction pattern that forms an X –> Rosalind Franklin’s X-ray diffraction of DNA showed an X
Meselson-Stahl results
DNA has heavy banding at beginning –> first generation has halfway between heavy and light –> after two generation some are intermediate and some are light
DNA backbone
ribose sugar + phosphate
ribose, -OH at 2’
2-deoxyribose; no -OH at C2
linkage between ribose sugar and phosphate
phosphodiester linkage
purines
two rings, A and G
pyrimidines
1 ring; T and C and U
adenine
